Data is stored on magnetic media by writing on the magnetic media using a write head. Magnetic media can be formed in any number of ways, such as tape, floppy diskette, hard disk, or the like. Writing involves storing a data bit by utilizing magnetic flux to set the magnetic moment of a particular area on the magnetic media. The state of the magnetic moment is later read, using a read head, to retrieve the stored information.
Conventional thin film read heads employ magnetoresistive material, generally formed in a layered structure of magnetoresistive and non-magnetoresistive materials, to detect the magnetic moment of the bit on the media. Shields commonly are formed on either side of the magnetoresistive structure to inhibit the magnetic flux of adjacent bits from being detected by the magnetoresistive structure. The shields are located close to the magnetoresistive materials to allow for more closely space bits on the media.
A sensing current is passed through the magnetoresistive material to detect changes in the resistance of the material induced by the bits as the media is moved with respect to the read head. The magnetoresistive effect, given by .DELTA.R/R, typically is detected by passing a sensing current through the sensor along the plane of the layers.
One problem with devices having this structure, particularly in giant magnetoresistive devices, is that because the sensing current is allowed to flow through the layers in parallel, shunt current passes through layers of non-magnetoresistive. The shunt current, reduces the magnetoresistive effect of the sensor.
As an alternative to this structure, the leads may be arranged so that the sensing current passes through the sensor perpendicular to the plane of the layers. By passing the sensing current perpendicular to the plane, shunt current through the non-magnetic layers can be eliminated.
Current perpendicular to the plane devices or CPP devices, while overcoming some problems associated with the current in the plane or CIP devices, have other design problems. For example, U.S. Patent entitled MAGNETORESISTIVE TRANSDUCER WITH FOUR-LEAD CONTACT, by David Richardson, et al., S/N 09/006,307, filed on Jan. 13, 1998, issued as U.S. Pat. No. 5,959,811 on Sep. 28, 1999, herein incorporated by reference in its entirety, describes problems associated with providing electrical contacts to the magnetoresistive sensors. With CPP devices, because the thin film layers have such a low resistance perpendicular to their plane, the resistance of the sensing leads significantly reduces the magnetoresistive effect of the device.